The use of a fusing member constructed with a non-stick material as a top layer and a heat resistant base layer has been known in the reprophotographic art. Typical non-stick materials which have been used include polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), perfluoroalkoxy (PFA), polychlorotrifluoroethylene (ECTFE), ethylene-chlorotrifluoroethylene (ECTFE), ethylene-tetrafluoroethylene (ETFE), polyvinylidene fluoride (PVDF) and polyvinyl fluoride (PVF), silicone compounds and blends of these materials.
Fluoropolymer resin by itself, though an excellent non-stick material, provides no compliance. Silicone compounds on the other hand, while compliant are readily adversely affected by silicone oil which is commonly used as a release agent in fusing applications. As the silicone compound swells, the nip characteristics change, affecting the fuse quality of the images. The silicone coating becomes susceptible to mechanical damage, such as abrasion by the print media, picker fingers and hardened toner that accumulates in the system. Fluoroelastomers, on the other hand are tougher materials which are more resistant to silicone oil. However, fluoroelastomers generally require a special oil to function in a fuser application. These special silicone oils are costly and when present on the copy media make writing on the media noticeably more difficult.
It is preferable to have a material combining the non-stick properties of fluoropolymer resins and the compliant properties of silicone elastomers. U.S. Pat. No. 3,435,500 to Aser and U.S. Pat. No. 4,789,565 to Kon disclose applying a polytetrafluoroethylene resin to a silicone rubber surface which is adhered to a metal insert and sintering the resin. Another U.S. Pat. No. 5,547,759, to Chen, et al. discloses a method of bonding a fluoropolymer resin to various substrates including silicone, via a layer of fluoroelastomer and fluoropolymer containing a polyamide-imide layer. The fluoropolymer in the latter case assumes the role of an insulator to prevent degradation of the compliant substrate and the adhesion between the layers during the sintering process.
Since most commercially available materials today compromise one necessary property in some way or another, the various solutions suggested in the prior art are not fully satisfactory. This is particularly true in color systems where gloss and gloss maintenance is a key element of the fusing system. Here, a fluoropolymer coating possessing easy wettability by a silicone release agent is a highly desirable surface characteristic.
Accordingly, it remains highly desirable to provide a fuser member where the top layer provides maximum release properties and is not affected by the use of release agents commonly in use as well as possessing compliant properties.